diff mbox series

[5.4,120/134] mm/slub: fix a memory leak in sysfs_slab_add()

Message ID 20200616153106.532769297@linuxfoundation.org
State Superseded
Headers show
Series None | expand

Commit Message

Greg KH June 16, 2020, 3:35 p.m. UTC 
From: Wang Hai <wanghai38@huawei.com>

commit dde3c6b72a16c2db826f54b2d49bdea26c3534a2 upstream.

syzkaller reports for memory leak when kobject_init_and_add() returns an
error in the function sysfs_slab_add() [1]

When this happened, the function kobject_put() is not called for the
corresponding kobject, which potentially leads to memory leak.

This patch fixes the issue by calling kobject_put() even if
kobject_init_and_add() fails.

[1]
  BUG: memory leak
  unreferenced object 0xffff8880a6d4be88 (size 8):
  comm "syz-executor.3", pid 946, jiffies 4295772514 (age 18.396s)
  hex dump (first 8 bytes):
    70 69 64 5f 33 00 ff ff                          pid_3...
  backtrace:
     kstrdup+0x35/0x70 mm/util.c:60
     kstrdup_const+0x3d/0x50 mm/util.c:82
     kvasprintf_const+0x112/0x170 lib/kasprintf.c:48
     kobject_set_name_vargs+0x55/0x130 lib/kobject.c:289
     kobject_add_varg lib/kobject.c:384 [inline]
     kobject_init_and_add+0xd8/0x170 lib/kobject.c:473
     sysfs_slab_add+0x1d8/0x290 mm/slub.c:5811
     __kmem_cache_create+0x50a/0x570 mm/slub.c:4384
     create_cache+0x113/0x1e0 mm/slab_common.c:407
     kmem_cache_create_usercopy+0x1a1/0x260 mm/slab_common.c:505
     kmem_cache_create+0xd/0x10 mm/slab_common.c:564
     create_pid_cachep kernel/pid_namespace.c:54 [inline]
     create_pid_namespace kernel/pid_namespace.c:96 [inline]
     copy_pid_ns+0x77c/0x8f0 kernel/pid_namespace.c:148
     create_new_namespaces+0x26b/0xa30 kernel/nsproxy.c:95
     unshare_nsproxy_namespaces+0xa7/0x1e0 kernel/nsproxy.c:229
     ksys_unshare+0x3d2/0x770 kernel/fork.c:2969
     __do_sys_unshare kernel/fork.c:3037 [inline]
     __se_sys_unshare kernel/fork.c:3035 [inline]
     __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3035
     do_syscall_64+0xa1/0x530 arch/x86/entry/common.c:295

Fixes: 80da026a8e5d ("mm/slub: fix slab double-free in case of duplicate sysfs filename")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Link: http://lkml.kernel.org/r/20200602115033.1054-1-wanghai38@huawei.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 mm/slub.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Linus Torvalds Jan. 28, 2021, 5:06 p.m. UTC | #1 
Note: this patch is getting reverted upstream, because it causes a
double free (admittedly under very rare circumstances, but still).

I'll mark the revert for stable, since it seems to have made it into
basically all stable kernels.

The revert commit is 757fed1d0898 Revert "mm/slub: fix a memory leak
in sysfs_slab_add()".

            Linus

On Tue, Jun 16, 2020 at 8:41 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>

> From: Wang Hai <wanghai38@huawei.com>

>

> commit dde3c6b72a16c2db826f54b2d49bdea26c3534a2 upstream.
diff mbox series

Patch

--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5776,8 +5776,10 @@  static int sysfs_slab_add(struct kmem_ca
 
 	s->kobj.kset = kset;
 	err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name);
-	if (err)
+	if (err) {
+		kobject_put(&s->kobj);
 		goto out;
+	}
 
 	err = sysfs_create_group(&s->kobj, &slab_attr_group);
 	if (err)